簡中We plated prostate cancer metastasis samples, freshly collected by tissue biopsy and confirmed by pathology review to have >10% tumor cell content, into prostate organoid culture and established organoid lines from six patients that have been continuously propagated for >6 months. A seventh organoid line was established from circulating tumor cells (CTCs) of a CRPC patient with a high CTC count (>100 cells per 8 ml of blood). The clinical characteristics and prognostic variables (Smaletz et al., 2002) of the seven patients span the spectrum of advanced prostate cancer (Table 1).

In our hands, the efficiency for establishing continuously propagated organoid lines from metastatic biopsies was ∼15%–20% (6 lines from 32 “attempts” of cancer-bearing samples) and could presumably be improved by further optimization of growth conditions. It is worth noting that tumor organoids were reproducibly maintained for 1–2 months for ∼70% of soft tissue tumor biopsies and ∼30% of bone biopsy biopsies, but many of these tumor cultures were overtaken by tumor-associated spindle cells or normal epithelial cells present in the biopsy material. For example, two continuously proliferating organoid lines derived from liver and lung metastases had no copy number alterations and no mutations of 50 common cancer-associated genes (not shown), which we interpret as more consistent with the lines originating from normal liver or lung epithelial cells rather than from prostate cancer. Indeed, others have reported that the growth conditions used here are broadly conducive to growth of multiple normal epithelial cell types (Barker et al., 2010; Huch et al., 2013a; Huch et al., 2013b ; Sato et al., 2009). Strategies to selectively isolate tumor from the normal epithelial and stromal cells present in biopsies might overcome this problem. In addition, evaluation of other conditions to improve primary epithelial growth such as coculture with stromal cells and ROCK inhibitor (Liu et al., 2012b) might further enhance efficiency. Nonetheless, the derivation of seven new lines over ∼9 months effectively doubles the number of existing